Use Javascript, and React (or even Vue, seems popular as well). Code everything server and client side in the same language, and you can even re-use code client- and server side (the infamous "common" folder). Then WHEN or IF you have enough success that scalability or a huge userbase makes it practical, then you can become a language snob and reimplement everything natively on whatever computer you are running on. javascript+node.js is good enough to move really fast and you can focus on building a userbase before becoming bogged down in learning a bunch of "not needed yet" stuff. You'll do better with flexible technology you know really well and can use everywhere rather than having to learn the "optimal choice" for every little sub-decision you need to make on your journey.